Copiapoa melanohystrix Photo by: Flavio AgrosiCopiapoa melanohystrix should be distinguished by its more long and stout black spines and blackish felted areoles that give the plant a very intriguing dark overall.

Origin and Habitat: Esmeralda and adjacent areas.Altitude: 300-600 metres above sea level.Habitat: It grows in areas where very little else grows. It's a very drought tolerant species. Despite the lack of rain where it lives, the extreme aridity is attenuated by the frequent, often dense, coastal fogs. The fog tends to shows a recurrent pattern; usually it is overcast in the early mornings, the clouds dissipating during the late morning and returning during the late afternoons. Even though the temperatures are moderate in the summer as well, the light on sunny days is so bright and burning that most Copiapoas are covered by a white waxy surface which protects the plants from the sun and reduces the evaporation. The wax gives the plants a characteristic, whitewashed look. The waxy coating is only created if the plants are exposed to ultraviolet rays and will only be created sporadically under glass in a greenhouse.

Description: The name Copiapoa melanohystrix is one of the many forms of the very variable Copiapoa cinerea/Copiapoa columna-alba complex. It is still unclear whether this variable complex is one or several species. There is so much variation that most authors choose to lump them together. Copiapoa melanohystrix should be distinguished by its more long and stout black spines and blackish felted areoles that give the plant a very intriguing dark overall. It can be referred to a form or clonotype within the variability of Copiapoa columna-alba. This form is more decorative than the standard Copiapoa cinerea and one of the showiest of all cacti.Habit: Usually solitary, forms white columns with dark contrasting spination. Stem: Variable 50-75 cm tall, 10-20 cm in diameter, epidermis covered with a thick stratum of ashy-white pruine. Apex flattened with abundant dark-grey wool and without spines.Ribs: 27-47, depressed, obtuse and tuberculated, approx 1 cm wide, 5-7 mm tall. Inter-ribs suture wavy.Areoles: Small (diameter 2-3 mm), oblong, with yellow-orange wool (later becoming grey) recessed within the lower part of tubercle, 4-8 mm apart.Central spines: 1-3 sub-erected, strong, more than 2 cm long, black. Radial spines: 4-5 thin and arching, 5-8 mm long. Normally not present in adult specimen.Roots: Not napiform.Flowers: Diurnal closing at night, protracting the period of opening many days and arising on the crown, often several at a time, funnel form, small (2-3 cm long), yellow, scentless.Fruit: Deeply concealed within the apical wool, round or egg-shaped, pale green reddening toward the apex, almost naked with only few (3-4 mm long) scales. Almost completely dry at maturity.Seeds: Shining-black.

Subspecies, varieties, forms and cultivars of plants belonging to the Copiapoa cinerea group

Copiapoa cinerea(Phil.) Britton & Rose: Produces chalky/white stems covered with wool at the apex, which contrasts well with the sparse, jet-black spines. It is a solitary, or slowly offsetting, globular to columnar cactus.

Copiapoa cinerea subs. columna-alba(F.Ritter) D.R.Hunt: Usually solitary, forms white columns. All the plant in habitats lean markedly northward toward the sun following the direction of predominant wind, leading to the illusion that the entire landscape is tilted.

Cultivation and Propagation: Considering that Copiapoa melanohystrix comes from a habitat with an extremely arid climate, they are remarkably tolerant of pot culture. These plants have taproots and are susceptible to overwatering. They requires also an appropriate air circulation. Copiapoas are summer grower species easy to cultivate.Growth rate: This is a slow growing cactus kept for the beauty of its form that will make clumps given the best conditions. Soils: It likes very coarse mineral cactus mix soil, but can become too elongated if compost is too rich.Repotting: Use pot with good drainage.Watering: It requires light but regular waterings in summer, but let the soil mix dry between waterings, but do not overwater (Rot prone), it must be strictly kept dry throughout the winter quiescent period since it is very sensitive to any moisture excesses keep dry in winter. Fertilization: Feed with a high potassium fertilizer in summer. Hardiness: Not highly tolerant of a great deal of frost. They need to be kept in a cool place during winter rest and are resistant to light frost if kept on the dry side prior to, and during, cold weather ( they are hardy to -2 C ° C short periods). However some warmth throughout the year will increase the grower's success (minimum 5° to 10°C during rest season). Exposition: Requires full sun or light shade and careful watering to keep plant compact with strong coloured spines. Tends to bronze in strong light, which encourages flowering and heavy spine production. Light shadow my be useful in the hottest summer days.Uses: It is an excellent plant for container growing. It always looks good and stays small. It look fine in a cold greenhouse and frame or outdoor in a rockery.Pests & diseases: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for: - Red spiders: Red spiders may be effectively rubbed up by watering the infested plants from above.- Mealy bugs: Mealy bugs occasionally develop aerial into the new growth among the wool with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects. - Scales: Scales are rarely a problem. It is wise to treat your whole collection with a systemic insecticide twice a year in spring and autumn. - Rot: Rot is only a minor problem with cacti if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much. To prevent rottenness it is also advisable to surround its root neck by very rough sand or grit, this help a fast water drainage.Propagation: Seeds (or offsets if available), Grafting is often used to speed growth rate and to create a back-up to plants in collection. Seeds germinate in 7-14 days at 21-27° C in spring, remove gradually the glass cover as soon the plants will be well rooted (ca 1-2 weeks) and keep ventilated, no full sun for young plants!